The present invention relates to a method of producing webs of material that have discrete pieces of material mounted thereon. The invention also relates to an arrangement for carrying out the method.
The manufacture of certain sheets of material that are intended for the production of absorbent articles for instance, such as diapers, sanitary napkins, incontinence protectors, panty liners and like articles, sometimes comprises mounting and bonding discrete pieces of material on and to travelling webs of material. These discrete pieces are normally glued to the web, although they may alternatively be welded, there being required several so-called anvil rolls against which the travelling web is pressed and passes tangentially thereto or is partially embraced by one of the anvil rolls carrying said pieces of material, wherewith said pieces are brought into contact with the travelling web by means of said anvil roll.
The transfer of cut pieces of material from the anvil roll to the travelling web is often facilitated with the aid of glue or some other adhesive agent In this regard, the cut pieces of material are adhered to the anvil roll and then transferred to the travelling web as said web lies against the anvil roll, by virtue of rotation of said roll. The use of glue in this process increases the xe2x80x9cstop timexe2x80x9d and therewith lowers productivity and also increases material consumption, which has a negative affect on the price of the product, among other things.
JP-A-8052696 describes a cutting unit for cutting sanitary articles from a roll of material. The cutting unit includes an anvil roll and a cutting roller which are arranged opposite one another. The sanitary articles cut from the reel of material are sucked firmly to the surface of the cutting roller and transferred to a feed roll.
One problem associated with the use of the same anvil roll for cutting (clipping), transferring and bonding the pieces of material to the web is that an adhesive agent, such as glue, is required to this end. If the pieces of material are to be welded to the web for instance, it is necessary in the case of present technology to hold the loose pieces of material firmly during different transfer occasions between several anvil rolls. This requires the provision of more equipment and impairs the accuracy in which the pieces of material are applied to the web, resulting in poorer product quality.
It is thus desirable to be able to utilise one and the same anvil roll for all phases without needing to use glue or any other adhesive agent.
The object of the invention is to solve the aforesaid problems. This object is achieved in accordance with the invention with a method and with an arrangement for producing webs of material that have pieces of material mounted thereon, said method and arrangement comprising the use of one single anvil roll which cuts, accelerates, transfers and joins the discrete pieces of material to the travelling web in the absence of glue or any other adhesive agent The pieces are mounted on the web by virtue of the anvil roll comprising means for holding said pieces against the anvil roll subsequent to cutting out said pieces, for transferring said pieces to the travelling web and for fastening said pieces thereto.
According to one preferred embodiment of the invention, the method comprises the steps of:
cutting discrete pieces from at least one material with the aid of cutting means, preferably in the form of a rotating cutter roll while using the anvil roll as a counterpressure means;
firmly holding and applying said discrete pieces onto at least one web of material that moves against the anvil roll, by using the anvil roll as a transfer element;
fastening said discrete pieces to said at least one travelling web with the aid of fastener means, wherein said pieces are mutually separated by cutting, accelerated whilst firmly held and then fastened or bonded to said at least one web of material, without the use of adhesive agent, through the medium of one and the same anvil roll and by means of said fastening means whilst using the anvil roll as a counterpressure, means even when fastening said discrete pieces to said web, and wherewith the discrete pieces are held firmly by means of holding means provided on the anvil roll, said pieces and said web running together against the anvil roll before and after bonding of said pieces to said web.
According to another preferred embodiment of the invention, the arrangement for carrying out the method includes an anvil roll which is rotatable about its longitudinal axis and which is partly embraced by or tangential to said at least one web of material and which carries sequentially in its direction of rotation means for cutting discrete pieces from at least one material, and means for fastening or bonding said discrete pieces to said web, wherein the anvil roll includes between said cutting means and said fastening means further means which function to hold the discrete pieces of material against the roll prior to fastening said pieces to said web with the aid of said fastening means.
The pieces of material are preferably held to the anvil roll by suction, wherewith the means for holding said pieces may, for instance, comprise vacuum generating means, means that utilise static electricity or a mechanically working device.
The pieces are preferably fastened to the web by welding, such as ultrasound welding, or by some other type of heat-applying method and/or device, such as a hot roll, laser, thermobonding device, etc.
A significant advantage afforded by the inventive method and the inventive arrangement resides in the simplification that is achieved with the use of solely one single anvil roll for all of the steps involving cutting, accelerating, and transferring pieces of material to the travelling web of material and fastening said pieces to said web. A farther advantage is that it is not necessary to use glue or some other adhesive agent to fasten said pieces to the web. Furthermore, since the pieces of material and the web runs together against the anvil roll before and after bonding it is easy to control and synchronise the feeding thereof to the bonding device and allow ample time for cooling of the bonds.